How much scientific evidence is there for and against the assertion（断言，声明） that exposure to video game violence can harm teens? Three researchers have developed a novel method to consider that question: they analyzed¹ the research output of experts who filed a brief in a U.S. Supreme² Court case involving violent video games and teens.

Their conclusion? Experts who say violent video games are harmful to teens have published much more evidence supporting their claims than have experts on the other side of the debate.

"We took what I think is a very objective approach: we looked at the individuals on both sides of the debate and determined³ if they actually have expertise⁴ in the subjects in which they call themselves experts," said Brad Bushman, co-author of the study and professor of communication and psychology⁵ at Ohio State University.

"The evidence suggests that those who argue violent video games are harmful have a lot more experience and stronger credentials⁶（证明） than those who argue otherwise."

Bushman conducted the study with Craig Anderson, professor of psychology at Iowa State University, and Deana Pollard Sacks, professor of law at Texas Southern University. Their research will be published in May in the Northwestern University Law Review Colloquy⁷.

Their study involved Schwarzenegger v. Entertainment Merchants Association, a case before the U.S. Supreme Court that will decide whether the state of California can ban the sale or rental⁸ of violent video games to children under 18. The court is expected to rule on the case this summer.

In this case, groups supporting and opposing the law have filed what are called briefs of amicus curiae（法官的顾问） . These are briefs by people or groups who are not involved directly in the case, but want to offer the court their expert opinion on the issues involved.

The researchers analyzed the credentials of the 115 people who signed the Gruel⁹ brief, who believe video violence is harmful, and the 82 signers of the Millett brief, who believe video violence is not harmful. (The briefs are named after the lead attorneys for each side.)

The data for the study came from the PsycINFO database, which provides more than 3 million references to the psychological literature from the 1800s to the present, including peer-reviewed journal articles, book chapters or essays, and books.

For each of the signers of the two briefs, the researchers calculated how many articles and books they published on issues relating to violence and aggression¹⁰ in general and on media violence specifically.

The results showed that 60 percent of the Gruel brief signers (who believe video game violence is harmful) have published at least one scientific study on aggression or violence in general, compared to only 17 percent of the Millett brief signers.

Moreover, when the researchers looked specifically at the subject of media violence, 37 percent of Gruel brief signers have published at least one study in that area, compared to just 13 percent of the Millett brief signers.

In a further analysis, Bushman and Anderson examined where the signers of both briefs have published their research. The best academic journals have the highest standards and the most rigorous peer review, so only the best research should be published there, Bushman said.

The researchers used a well-established formula, called the impact factor, to determine the top-tier journals, and then calculated how many signers had published in these journals.

Results showed that signers of the Gruel brief had published over 48 times more studies in top-tier journals than did those who signed the Millett brief.

"That's a staggering（蹒跚的，令人惊愕的） difference," Bushman said. "It provides strong support for the argument that video game violence is indeed harmful."

Bushman said he and his colleagues did this study because they wanted to show that there is a way for the Supreme Court to evaluate the contradictory¹¹（矛盾的，反对的） evidence it has been presented.

"The justices were presented with two briefs, arguing opposite sides, and they may think the contradictory briefs simply cancel each other out," Bushman said.

"We just wanted to point out to the justices that not all briefs are the same. In this case, the credentials and experience of those who signed the Gruel brief far exceeds that of the ones who signed the Millett brief."